Personalized 3D-printed Headgear for Multi-electrode Transcranial Electrical Stimulation

Our program really has two primary goals. The first is to identify changes in the brain that are leading to cognitive and emotional deficits in those across the dementia spectrum. The second goal builds directly on this by using those changes that we just identified as treatment targets, using techniques like neuromodulation in order to improve everyday functioning.

Our innovative headgear and training process enable easy, accurate, multi-electrode setup remotely. This expands access, while preserving and even improving simulation precision. To begin, acquire a structural T1 MRI scan.

Upload the participant's T1 to a secure server, and use segmentation software to segment the brain tissues and prepare the model for the computational modeling steps. Launch the ROAST program. Develop an individualized computational model of electric current flow through the participant's head.

Using the model, place electrodes in locations that direct the current flow to the target brain area. Now, upload the desired electrode locations and participant's T1 into the headgear creation software. The software will automatically place crossbars, connecting the electrode holders, to form a rigid shell that allows the user to reposition hair and identify anatomical landmarks.

Upload the 3D model file in stl format to an appropriate 3D printer. Once printed, ensure rough edges are smoothed using sandpaper when necessary. Place the headgear on the research participant's head using the orienting tabs to guide placement.

Secure the headgear using a hook and loop strap under the chin for bilateral headgear. Check the fit of the headgear by looking for minor gaps between the electrode holders and scalp. Note the locations where minor gaps occur, and remove the headgear to apply soft spacers that will compensate for these gaps.

Check the fit again to ensure that all other electrode holders remain in contact with the scalp. To validate the measurement accuracy of the headgear, use a flexible tape measure to hand measure and mark the location of each electrode on the participant's head. Place the headgear on the participant.

Then, mark the locations of each electrode holder. Remove the headgear. Measure the difference in millimeters between the hand measured marks and the headgear electrode holder marks.

Record the distance and direction of any differences. Once the headgear is properly fitted, move any loose hair out of the electrode holder to expose as much skin as possible. Then, fill each electrode holder with conductive gel and place each electrode into its holder, ensuring contact between the electrode and the gel.

Apply the cap to the holder to secure the electrode in place. On the first session, begin with explaining the components of the headgear and demonstrate proper placement and preparation procedures to the study partner. Inspect the fit of the headgear for minor gaps.

If gaps exist, apply flexible spacers to the bottom of the electrode holder and recheck other electrode holders. Demonstrate best practices, including moving hair from under holders, properly filling with gel, placing electrodes, and applying the corresponding holder cap. Now, demonstrate the operation of the ME-tES device:battery charge check and the evaluation of electrode impedance.

Then show proper rotations, removal, and washing and drying methods. For the next session, have the study partner mark the nasion and auricular points to ensure the headgear-orienting tabs are properly placed on the participant's head. Then, have the study partner place the headgear.

Mark the electorate holder locations of the study partner's placement, and then remove the headgear. Next, place the headgear on the participant's head, mark the locations of the electorate holders, and remove the headgear. Note any differences in both placements and provide any corrective feedback.

Have the study partner conduct the entire setup, including activating the device, evaluating impedance, and cleaning equipment under supervision. In subsequent sessions, use a standardized skill-based checklist to monitor the study partner during each step of the setup process. On the final day of training, provide the study partner with a carrying case containing all necessary supplies, a care and maintenance manual, and a second case with the ME-tES device at the end of the session.

For remote at-home ME-tES sessions, have the study partner log into a secure video call. Ask them to perform all setup activities. Then, have them report impedances.

Once acceptable, provide a code for the study partner to enter into the ME-tDCS unit. Then, perform the required session activities on a video call. Once the session is complete, ensure that the study partner follows the care and maintenance checklist and charges the stimulator batteries.

The headgear electrode locations differed by an average of only 8.6 millimeters across the first 54 participants, relative to hand-measured locations obtained by the study team. On the first day of training, study partners placed the headgear with an average deviation of approximately only three millimeters relative to study team placement, which improved to a nominal 1.74 millimeters by the final day. Participants and study partners reported high levels of confidence after the first session, which further increased to near-ceiling levels by the final training session.

Our patented headgear provides a truly personalized method that enables the safe and precise delivery of multi-electrode neuromodulation. The headgear is very user-friendly to the point that non-experts, like family and friends, can deliver the multi-electrode stimulation remotely.